Identifying And Modeling Research On Reservoir Structural Fracture Of Chang4+5?Chang8 Oil-bearing Formation Of Yanchang Formation In Jiyuan-baibao Area,ordos Basin

Ordos Basin,as a polycyclic superimposed basin experienced multiple tectonic movements,has a large number of structural fractures in the sedimentary cap rocks.The Yanchang Formation in Jiyuan-Baibao area is one of the main target stratum for oil and gas exploration and development,so there must be a large number of structural fractures and the fracture system should be very complex.Due to the unique complexity of the structural fractures,the study of cracks becomes a worldwide problem.In this paper,taking the Chang 4+5~Chang 8 section of the Yancahng Formation in the Jiyuan-Baibao area as an example,we use a variety of materials such as field outcrops,core observations,and imaging logs to study the fracture systems that have developed in it.The development features of structural fractures in the Chang 4+5~Chang 8 formation of the study area were basically studied clear.The results of the study indicate that the Chang 4+5~Chang 8 section of the Yancahng Formation in the Jiyuan-Baibao mainly has two(four groups)X-type conjugate cracking systems,which are the NEE-NW direction and NNW-NE direction.Among them,the NEE direction and NNW direction fractures are the most developed.Most of the cracks developed in the study area are high-angle cracks,the number of diagonal cracks is in the second place,low-angle-near-horizontal cracks are less developed.Most of the cracks are open high-seam joints,and there are less closed joints and filling joints.Most of the filling material is bitumen,calcite,and argillaceous matter.The extension length of the fracture plane is in the range of 2.5m~30m,the longitudinal depth of fractures is in the range of 0.6m~2.8m,the width of the fracture is in the range of 0?m ~400?m,the peak value is in the range of 0?m~100?m,and the fracture porosity is between 0%~0.59%.Tectonic movement,lithology,and layer thickness are the most critical factors for the fracture development.The fractures are mostly in the rock formation and terminate at the boundary of the rock formation.The fractures are obviously controlled by the stratum and the distribution of cracks in the longitudinal direction shows significant heterogeneity.The latest DFN discrete fracture network modeling technology is used to study the development of the G29 well area and to establish a three-dimensional geological model and equivalent fracture property model that can quantitatively characterize and describe structural fracture systems in wells and even unknown regions in the study area.This contributes to further understand the true development status of fractures in the ground,predicting the favorable zones for fracture development,exploring the law of fracture development,revealing the role of fractures in improving the reservoir space and seepage capacity.And that it is very important to improve the exploration and development of reservoirs and increase recovery.